Support for South Africa’s ruling African National Congress (ANC) is plunging and a party backed by former President Jacob Zuma may become the country’s third-biggest after next month’s election, a new opinion poll shows.

The ANC, which has ruled South Africa since the end of apartheid, may garner just 37% support in the May 29 vote, while Zuma’s uMkhonto weSizwe Party, or MKP, may get 13%, the Social Research Foundation (SRF) said in comments sent to Bloomberg on Wednesday, citing a poll it carried out this month.

Such a result may mean the ANC has to form a coalition with a large party in order to retain control of Africa’s biggest economy. Zuma’s decision to back the MKP has eaten away at the ANC’s support. He ruled the country from 2009 to 2018, when the ANC forced him from office.

The poll of 1,835 registered voters across the country also found that the main opposition Democratic Alliance would win 25% of vote, the Economic Freedom Fighters 11% and the Inkatha Freedom Party 5%. The Freedom Front Plus and Action South Africa would both get 2%, it showed.

As recently as mid-January, before it carried out its surveys, the SRF had predicted that the MKP would get just 1% to 2% of the national vote.

The results of the survey are another indicator of the ANC’s decline amid corruption scandals, severe power outages, rampant crime and the collapse of basic services such as water provision. In the 2019 election, the party won 57.5% of the vote, its lowest share since taking power in 1994.

The poll was based on an estimated turnout of 66% and has a 2.2% margin of error.

The SRF, a public-policy organisation, was founded in 2021. Its head, Frans Cronje, a former chief executive officer of the Institute of Race Relations, has consulted for South Africa’s biggest political parties, companies and richest people.